Drive Add-ons for PLCs.

Over the years, we came across situations where the OEM wanted to use his PLC to give the programmable command to the Stepper motor Drive and run the motor. This section features our drives which are quite compatible with the PLCs. These have certain add-on features which enable them to sync with the PLC generated signals for smooth functioning of application.

1. Start and Stop by Sensor
There are applications which require the drive to start and stop through PLC digital outputs. Thus here, we offer a drive with a built-in oscillator. In case you want to start with PLC and stop on sensor, then that too is possible. Drive will run at fixed set speed.

2. Speed Proportional to Analog Input
Some applications require the stepper motor to run in proportion to the analog input like 4-20 milliamps or 0-10 Volts. For such cases, we offer an in-built control card with our drive.

3. Speed Selection by Digital Inputs
We can offer a drive with a facility to change the speed of stepper motor by PLC. A drive will have digital inputs that can be selected by using digital outputs from PLC.

4. Clock-out for counting by Master Controller.
The applications which require a PLC to control the motion of stepper motor, we can offer our model where we use a built-in oscillator, but the no of steps given to the drive can be given out to the PLC. Using these pulses as a counter, it can stop the motion.

Q & A for PLC system integrators

Scenario-1

Q. In one of my projects, I am using a lower end PLC. I have only digital outputs. It’s difficult to provide frequency output from this model but I need measured traverse. Do you have a solution?

Yes sir. There are in fact two options. In first option you can use our CTL (cut-to-length) controller. Give a start (run) signal from PLC and the CTL will manage everything else. CTL has a built in HMI and relay outputs and many other features. But this one, sure is more expensive of the two options.
If the end use does not justify the cost, there is one more way. We will generate the clock when a run input is received and give you a clock output. This clock out can be counted by your PLC and decision about stoppage, direction change or slow down can be taken by the PLC accordingly. Thus in this case 3 digital inputs will be required from PLC – start, direction and slow down. Slow down may not be required if the speeds are lower than 60 RPM. This is extremely economic solution, which allows a use of lower end PLC.

Scenario-2

Q. And if analog signal of 4 to 20 mA is available, can you give proportional speed?

Of course!! Only thing is that you will have to specify the speeds at 4 and 20 mA input. If direction reversal is essential, momentary slow down and re-acceleration to original speed can be incorporated. It is advisable to use a start signal too, so that frequency output at 4 mA input will not cause any motion at the lowest speed.

Scenario-3

Q. We are using a advance model of PLC and have PWM outputs.

In that case you can directly interface the drive with PLC. Sourcing or sinking outputs can be interfaced. But the most important thing to remember is that if you wish to achieve high speeds, a proper acceleration and retardation must be provided, which takes care of the properties and parameters of motor and mechanical system. Starting and stopping at base speed of 60 RPM is important to achieve desired performance.